"For any given pair of birds, Biro says, "you can accurately work out which of them is the leader and which one of them is the follower."
Some birds had more followers than others. This demonstrates a hierarchy of influence within the flock. "You can actually rank birds in terms of the influence that they have on others within the group," Biro says. "Basically every individual gets a kind of a vote in what the flock does, but the weight of your vote depends on your rank, your position in the hierarchy."
And it did turn out that highly influential birds tended to fly out in front, according to a report on the study in the journal Nature.…"
Photo of common terns in flight by Max Skwarna: http://is.gd/bCqT9
Look at those aerodynamics!